CLEARCHUS, the son of Rhamphias, a Spartan general and condottiere. Born about the middle of the 5th century B.C., Cle archus was sent with a fleet to the Hellespont in 41I and became harmost of Byzantium. His severity, however, made him unpop ular, and in his absence the gates were opened to the Athenians under Alcibiades (4o9). Subsequently appointed by the ephors to settle the affairs of Byzantium and to protect it from Thracian attacks, he made himself tyrant, and, when driven thence by a Spartan force, fled to Cyrus (q.v.) . In the "expedition of the ten thousand," Clearchus led the Peloponnesians. On Cyrus's death Clearchus conducted the retreat, until, being treacherously seized with his fellow-generals by Tissaphernes, he was handed over to Artaxerxes and executed (Thuc. viii. 8, 39, 8o; Xen., Hellenica, i. 3, 15-19; Anabasis, i. ii.; Diodorus xiv. 12, Clearchus was a typical Spartan, an able and energetic soldier, but lacking refinement and humanity.